Reproductive behavior of the Atlantic silverside,Menidia menidia (Pisces,Atherinidae)

Synopsis The spawning behavior of the Atlantic silverside,Menidia menidia, was studied at two sites on the North Edisto River estuary in South Carolina. Prespawning schools moved back and forth along the shoreline as the time of high tide approached. Spawning runs took place in the upper intertidal zone at high tide.Spawning fish deposited their eggs on three types of substrates: 1) the lower stems of cordgrass plants,Spartina alterniflora, 2) detrital mats, and 3) exposed cordgrass roots along erosional scraps. Spawning behavior during egg deposition and fertilization was similar for all three substrates. Females released eggs during a rapid fluttering motion of the posterior half of the body. A similar movement accompanied release of sperm by males. Behavior of fish just prior to spawning insured deposition of gametes at locations that provided protection from thermal and drying stress during development. Eggs were deposited at mean intertidal elevations of 1.8 and 1.5 meters above mean low water (MLW) at respective study sites. They were exposed to the atmosphere for approximately ten hours between successive high tides.During spawning runs in which eggs were deposited at the base of cordgrass plants, ambient dissolved oxygen concentrations of the water in the spawning area were sometimes reduced to < 1.0 mg. 1^–1. Spent fish, apparently incurring an oxygen debt while spawning, formed a nonschooling aggregation offshore from the spawning zone.The recurrent use of specific spawning substrates for egg deposition resulted in an uneven distribution of spawning runs along the shoreline at each study site.Contribution No. 409 to the Gulf Breeze Environmental Research Laboratory. Contribution No. 377 to the Belle W. Baruch Institute for Marine Biology and Coastal Research.     

Interspecific variation in spawning time and male mating tactics of the parrotfishes on a fringing coral reef at Iriomote Island,Okinawa

Spawning time and male mating tactics of parrotfishes (family Scaridae) were investigated on a fringing coral reef at Iriomote Island, Okinawa. Spawning was observed in 14 species, and more frequently in more abundant species such as Chlorurus sordidus, Scarus rivulatus and Chlorurus bowersi. At the reef-edge spawning site, C. bowersi spawned at high tide, C. sordidus spawned both at high tide and in the early morning, whereas Calotomus carolinus and most of the Scarus species such as S. rivulatus spawned only in the early morning, mostly 0630–0830 h. Spawning only in the early morning irrespective of tide phase and moon age has seldom been reported from the scarid species of other localities. It is suggested that spawning in the early morning would be adaptive in species such as S. rivulatus, which migrated considerable distances (ca. 500 m) to the inshore feeding sites, in order to minimize feeding losses due to migration. For male mating tactics, pair spawning by territorial TP (terminal phase) males occurred in all 14 species, and streaking and group spawning by nonterritorial small IP (initial phase) males were seen more frequently in more abundant species. Moreover, group spawning by nonterritorial TP males, which were larger than the IP males but smaller than the territorial TP males, frequently occurred in S. rivulatus. Such mating tactics of TP males have not been reported from Scaridae.     

Diel and lunar spawning periodicity of the hawkfish Paracirrhites forsteri (Cirrhitidae) on the reefs of Kuchierabu-jima Island, southern Japan

We observed spawning behavior of the hawkfish Paracirrhites forsteri on reefs of southern Japan. Spawning generally occurred after sunset, prior to the full and new moon with semi-lunar spawning peak periodicity. No egg predation was observed in spawning after sunset, and high tide often occurred at dusk in the lunar phases. Thus, diel timing and lunar synchronicity may increase larval survival. We found that the mating activity tended to start earlier in the day during early mating season than during mid-to-late mating season. The advantages of the earlier start of mating activity were also examined in relation to adult biology contexts.     

Reproductive ecology of the Far Eastern catfish, Silurus asotus (Siluridae), with a comparison to its two congeners in Lake Biwa, Japan

Spawning activity of the catfish, Silurus asotus, takes place in temporary water (rice fields) from early evening to midnight, generally in connection with rainfall, from late April to late August. Spawning of the catfish was correlated with hydrographic parameters dependent on rainfall: daily precipitation, turbidity, water depth, and water temperature. The spawning habits of the catfish, and in particular the use of temporary waters such as rice fields that become submerged after rainfall or by irrigation, are presumed to be adaptations to the Asian monsoon climate with a pronounced rainy season. The apparent sex ratio of the catfish was extremely biased toward females. Intraspecific variation in the reproductive ecology, particularly mating behavior, of this species is observed among local populations. Factors that may have caused this variation are discussed in the context of a comparison of mating behavior, reproductive environment, and sex ratio between the Lake Biwa population of S. asotus and other conspecific populations, as well as two other species of silurid catfish that occur in the Lake Biwa drainage, S. biwaensis and S. lithophilus.     

Observations of spawning in the Leather Bass, <Emphasis Type="Italic">Dermatolepis dermatolepis</Emphasis> (Teleostei: Epinephelidae), at Cocos Island,Costa Rica

Courtship and spawning behavior is described for the Leather Bass, Dermatolepis dermatolepis, from observations made from a manned submersible at Cocos Island, Costa Rica on 19 days between November 2006 and February 2007. Spawning occurred in the evening (16:00–18:30 h) in subgroups of 10–32 individuals that formed within aggregations of 50–70 individuals. The mating sequence was characterized by subgroup formation and crowding behavior followed by a brief vertical spawning rush, gamete release, and the rapid separation of participants. The aggregation was present on all dives, and spawning was not restricted to specific lunar phases.     

Quantitative assessment of reproductive effort of the Manila clam Ruditapes philippinarum in a lagoon on Jeju Island (Korea) using enzyme-linked immunosorbent assay

We investigated gonad development and reproductive effort (RE) of the Manila clam Ruditapes philippinarum at Jeju Island, Korea. Gonad maturation and RE were determined using histology and an indirect enzyme-linked immunosorbent assay (ELISA). In June 2006, most of the clams (80%) in the lagoon were in the resting stage. Spawning clams first appeared in late July, and most clams spawned from early August to mid-September. The condition index increased gradually from early July to late August, then declined from early to mid-September, suggesting that spawning occurred during this period. The gonadosomatic index assessed by ELISA also increased dramatically from June (0.9), peaked in early August (19.7) then declined from late August to mid-September, indicating that clams at the study site had only one spawning pulse during the spawning period. Spawning at Jeju Island was one month later than Manila clams on the west coast of Korea. The delayed spawning and low RE of the clams could be in part, be explained by lower food availability, as the level of chlorophyll-a recorded in this study was much lower than that found in water from the west and south coast.     

Reproductive behaviour of the filefishRudarius ercodes: male spawning parades and female choice

Synopsis The reproductive behaviour ofRudarius ercodes is described from undersea observations in Aburatsubo Bay, Japan. Reproductive behaviour can be separated into four parts: (1) Prespawning Search = searching for spawning sites by females and searching for gravid females by males, (2) Spawning Parade = males follow a gravid female in a line, competing with each other to reach the head of the queue, (3) Spawning = the female takes the spawning position, males rush to the side of the female, and mating occurs between one female and several anterior males of the spawning parade, (4) Parental Care = females attach adhesive eggs to seaweed with the mouth and guard them until embryos hatch. There is no male parental care. The reproductive season ranges from May to October and spawning occurs early in the morning every day. Females begin feeding early in the morning, but males feed little at this time.R. ercodes shows neither territorial behaviour nor fixed-pair spawning. One male might spawn several times in one morning. One female spawns at most once every 5 days. The mating system of this species is promiscuous. The probable function of the spawning parade as a style allowing female choice is discussed.     

Mass spawning of Caesio teres (Pisces: Caesionidae) at Enewetak Atoll,Marshall Islands

Synopsis Mass spawning of Caesio teres occurred between March and August, 1983 on a reef emerging from deep water just inside the East Channel of Enewetak Atoll, Marshall Islands. Aggregations and spawning were observed from one day before until three days after the full moon. Spawning aggregations were not observed during the new or quarter moons. Spawning commenced after high tide, when the current began to flow out the pass from lagoon to ocean. The spawning aggregation of close to 1000 individuals migrated to the spawning site. Spawning occurred when the aggregate ascended to near the water's surface. Subgroups dashed horizontally within the aggregate, releasing a highly visible gamete cloud. Predation on spawning adults was not observed. Predation on spawned eggs was noted. The eggs of C. teres are described. Mid-Pacific Research Laboratory, Enewetak Atoll, Republic of the Marshall Islands Present address: Motupore Island Research Station, P.O. Box 320, University of Papua New Guinea, Papua New Guinea     

Spawning frequency, fecundity, egg weight and spawning type of silver pomfret, Pampus argenteus (Euphrasen) (Stromateidae), in Kuwait waters

Silver pomfret, Pampus argenteus, were collected by fishing with drift gillnets on one spawning ground in Kuwait waters during 1998–2000. Fish size frequency, sex ratio, maturation cycle, spawning frequency, fecundity and egg weight were assessed. The length–weight relationship differed between sexes whereby females were significantly bigger than males. Spawning started in mid‐May and continued until early October. During this time the water temperature ranged from 26.0 to 32.8°C, salinity was ? 39.0‰ and water depth ranged between 5 and 12 m. Large females spawned earlier than young spawners and the overall percentage of males during the spawning period was 70.3%. Spawning occurred after 13.00 h, with peak spawning between 15.00 and 18.00 hours during outgoing tide. Mean daily spawning frequency amounted to 63.2%. Spawning activity was found to be associated with the lunar cycle and spawnings were concentrated during the first and third quarters of the moon period, indicating a semilunar reproduction cycle. It was concluded that a female would spawn at least six times during the season. No change was observed in relative fecundity during the peak spawning season (June–August). Average relative batch fecundity was 176.3 eggs g^?1 somatic weight (SW), corresponding to a relative total fecundity of 1058 eggs g^?1 SW, which is 1.5 times higher than estimates obtained from counting the standing stock of oocytes. Bigger fish produced heavier eggs and the egg weight decreased as the spawning season progressed. Based on gonadal cycles, oocyte size frequency distribution and total fecundity, we concluded that silver pomfret is a multiple batch spawner with indeterminate fecundity.     

Spawning migrations in the monogamous butterflyfish,Chaetodon trifasciatus

Spawning and related behavior of a monogamous butterflyfish,Chaetodon trifasciatus, were observed at Kuroshima Island, Okinawa, Japan. Each heterosexual pair defended a feeding territory in the daytime. Spawning occurred at dusk on the days around full or new moon in the daytime. Spawning occurred at dusk on the days around full or new moon in the vicinity of offshore tidal currents. Spawning migration to such sites occurred in pairs, the feeding territories of which were located in areas of inshore currents. In the evening each pair established a small temporary territory, which they spawned adjacent to and slept within until the next morning. The distribution of sleeping sites as well as tidal current directions may determine the spawning sites of this butterflyfish.     

Spawning site selection by spotted seatrout,Cynoscion nebulosus,and black drum,Pogonias cromis,in Louisiana

Synopsis Spawning site selection by spotted seatrout and black drum was studied by locating drumming aggregations through the use of a hydrophone. From March 1987 to October 1990, 315 sound observations were made to identify and characterize spawning seasons and environmental requirements of both species in the Barataria, Caminada, and eastern Timbalier Bay systems of Louisiana. The sounds produced by the spawning aggregations were identified and verified against known recordings. Spawning was verified on several occasions by capturing and rearing zygotes (eggs) into identifiable larvae. Spotted seatrout formed drumming aggregations from late May to early October at salinities ranging from 7.0 to 25.8 ppt and temperatures from 24.5 to 33.5° C. Black drum formed drumming aggregations between January and April in salinities from 10.0 to 27.0 ppt and temperatures from 15.0 to 24.0°C. Large drumming aggregations of spotted seatrout were located from 1800 to 2400h and from 1800 to 2200h for black drum. Spotted seatrout aggregation size was highly correlated with water temperature and for black drum with dissolved oxygen concentrations. Spawning sites for both species were frequently located in deep moving water between barrier islands as well as in channels in open water where water depth ranged from 3 to 50 m. Spawning site selection depended on a particular range of environmental conditions and spawning locations varied seasonally and yearly depending upon hydrological variation.Correspondence to D.M. Baltz     

Reproductive behavior of the halfmoon grouper, <Emphasis Type="Italic">Epinephelus rivulatus</Emphasis>, at Ningaloo Reef,Western Australia

Behaviors associated with spawning by the halfmoon grouper, Epinephelus rivulatus, at Ningaloo Reef, Western Australia, are described from in situ observations made each evening throughout most of a lunar cycle. Spawning occurred after sunset on six consecutive evenings during the full moon period. During this time males were particularly aggressive toward one another and maintained high levels of activity among the gravid females that rested within each of their territories. Spawning occurred when a male swam alongside a responsive female and the pair rose in a tight spiral 1–1.5 m into the water column before releasing gametes and returning to the seabed. Spawning activity was followed by a longer nonspawning period (ca. 20 days), when fewer intraspecific interactions were observed and gamete reserves were replenished. Histological and behavioral evidence suggests that this cycle of spawning and replenishment may occur on a monthly basis. Although individual fish, particularly females, moved into certain areas to spawn, E. rivulatus did not form spawning aggregations as do larger species of grouper.     

Spawning ecology of flannelmouth sucker, Catostomus lattipinnis (Catostomidae), in two small tributaries of the lower Colorado River

We report the first published accounts of spawning behavior and spawning site selection of the flannelmouth sucker in two small tributaries of the lower Colorado River in the Grand Canyon, Arizona. Spawning was observed on 20 March 1992 and from 28 March to 10 April 1993 in the Paria River, and from 16 to 19 March 1993 in Bright Angel Creek. Flannelmouth suckers exhibited promiscuous spawning behavior–individual females were typically paired with two or more males for a given event and sometimes changed partners between events. Multiple egg deposits by different females sometimes occurred at one spawning site. Flannelmouth sucker selected substrates from 16 to 32 mm diameter in both streams. Spawning occurred at depths of 10 to 25 cm in the Paria River and 19 to 41 cm in Bright Angel Creek. Mean column water velocities at spawning locations ranged from 0.15 to 1.0 m sec^-1 in the Paria River and from 0.23 to 0.89 m sec^-1 in Bright Angel Creek. Water temperatures recorded during spawning ranged from 9 to 18° C in the Paria River and 13 to 15° C in Bright Angel Creek. Spawning flannelmouth sucker ascended 9.8 km upstream in the Paria River and 1.25 km in Bright Angel Creek. Spawning females (410–580 mm) were significantly larger than spawning males (385–530 mm) in the Paria River. The mean size of spawning fish in the Paria River was significantly smaller than the entire stock, averaged throughout the study period (380–620 mm). However, fish spawning in 1992–1993 averaged 53 mm larger than fish spawning in the same reach of the Paria River in 1981, indicating a shift in the size structure of this stock.     

Spawning behavior ofChaetodon multicinctus (Chaetodontidae); pairs and intruders

Synopsis Spawning by the banded butterflyfish,Chaetodon multicinctus (Chaetodontidae) was observed on coral reefs off Kona, Hawaii. These fish occurred in male-female pairs during normal daytime activities, a behavior which is typical for the family. Courtship is also a paired male-female activity. During spawning, however, other individuals (males?) may intrude on the spawning pair. Spawning typically takes place at least a meter or two above the bottom. The spawning position consists of the male below and behind the female with his snout against the female's ventral flank or anal fin area. Intruding individuals may join in when the pair is in position and about to spawn. Intruders line-up against the male in the same position as he is against his female. Underwater photographs are included to illustrate these behaviors.     

The Role of Temperature and Embryo Development Time in the Diel Timing of Spawning in a Coral-reef Damselfish with High-frequency Spawning Synchrony

We studied the diel timing of spawning in the demersally spawning Hawaiian damselfish, Dascyllus albisella, from mid-June to late-September 1997 at two small patch reefs in Hawaii. Our objectives were to elucidate daily timing of spawning in relation to water temperature, diel timing of hatching, and short-period spawning synchrony. Spawning occurred every 5–7 days at both reefs, with all spawning on a reef concluded either within a single day (1-day spawning) or within two successive days (2-day spawning). Spawning began in early morning and continued for most of the day. There was a significant, positive linear relationship between mean daily average water temperature (= daily average temperature averaged over the period starting from the day following the last spawning day of the preceding nest cycle till the day before the first spawning day of the current cycle) and peak spawning hour of day, for 1-day spawning, and the first and second days of 2-day spawning at both reefs. The relationship between mean daily average water temperature and peak spawning hour of day was comparable among all spawning-day classes and reefs. Hatching occurred on the fourth day of development throughout the study despite the 26.5–29.1°C change in water temperature during the study period, and hatching was restricted to within two hours after sunset. We propose that D. albisella's peak spawning time is positively correlated with increased water temperature because it maintains the benefits of synchronous spawning within two constraints: the narrow daily period of hatching, and the inverse relationship between water temperature and embryo developmental time.     

Identifying spawning behavior in Pacific halibut, <Emphasis Type="BoldItalic">Hippoglossus stenolepis</Emphasis>, using electronic tags

Synopsis Identifying spawning behavior in Pacific halibut, Hippoglossus stenolepis, is particularly challenging because they occupy a deep, remote environment during the spawning season. To identify spawning events, a method is needed in which direct observation by humans is not employed. Spawning behavior of seven other flatfish, species has been directly observed in their natural environment by investigators using SCUBA. All of these flatfish species display almost identical spawning behavior that follows a routine. Therefore, it is reasonable to believe that this spawning behavior occurs in other flatfish species, including Pacific halibut. As part of a larger study, we recaptured two Pacific halibut on which Pop-up Archival Transmitting (PAT) tags had been attached during the winter spawning season. Because the tags were physically retrieved, we were able to collect minute-by-minute depth records for 135 and 155 days. We used these depth data to tentatively identify spawning events. On seven separate occasions between 20 January 2001 and 9 February 2001, one fish displayed a conspicuous routine only seen during the spawning season of Pacific halibut and the routine parallels the actions of other spawning flatfish directly observed by humans using SCUBA. Therefore, we propose this routine represents spawning behavior in Pacific halibut. The second tagged fish did not display the conspicuous routine, thus challenging the assumption that Pacific halibut are annual spawners. PAT tags may prove to be a useful tool for identifying spawning events of Pacific halibut, and that knowledge may be used for improved management in the future.     

Combined effects of tidal and diurnal cycles on spawning of the puffer,Takifugu niphobles (Tetraodontidae)

Synopsis Spawning in the pufferTakifugu niphobles was observed at Tomioka in western Kyushu, Japan, and the factors affecting the spawning time were estimated using a multiple regression analysis. Spawning in this puffer occurred in the intertidal beach during evening rising tides around the full and new moons. Both the time of commencement and ending of a day's spawning were related mainly to the tidal cycle, and occurred later when the high tides occurred later. However, the termination of a day's spawning was also affected by the diurnal cycle; spawning ended earlier when sunset was earlier. Besides, a day's spawning tended to be concentrated within a shorter time span when the interval between the commencement of spawning and the sunset was shorter. Thus the spawning time of the puffer is regulated not only by the tidal but also by the diel cycle, and it is suggested that the adaptive significance of the spawning reactions to both cycles should be examined separately.     

Reproductive behavior of the Lake Malawi cichlid fish, <Emphasis Type="Italic">Tramitichromis intermedius</Emphasis>

Synopsis We studied the reproductive behavior of wild caught and captive-born, first generation offspring of the Lake Malawi fish, Tramitichromis intermedius(Teleostei, Cichlidae), held in aquaria. Spawning behavior includes an exchange of actions with dominant males performing bower construction and courtship behaviors while females focus on oviposition and mouthbrooding. Egg counts per oviposition and brooding and interbrooding periods of wild caught T. intermedius follow records of other mouthbrooding cichlid fishes. Observation of circling behavior suggests this behavioral trait may be used in mate choice as longer circling, indicating a secure territory and thus male dominance, leads to more oviposition events and hence the potential for larger broods. Comparisons of clutch size and total length of young at release from full-sized females vs. first spawners reveal smaller clutches and young from the younger females, most likely stemming from differences in body size. Investigation of spawning photoperiodicity also noted distinctions between the two groups with wild caught T. intermedius spawning activity peaking in the middle of the light cycle and captive-born, first spawners exhibiting no significant peak in activity. The trend to spawn midday is most likely influenced by predation factors, while the lack of a spawning periodicity in the offspring may be explained by developmental processes, the absence of environmental cues or the tendency for smaller males to be opportunistic in spawning events. The details of spawning behavior recorded in this study provide a database to investigate species differences and to indicate changes due to chemical and physical disturbances.     

Reproductive strategy and interspecific competition in the Lake-living gobiid fish isaza,Chaenogobius isaza

Isaza,Chaenogobius isaza, is a small gobiid fish endemic to Lake Biwa. It lives offshore throughout almost the entire year, showing a remarkable diel vertical migration. In early spring, males and females migrate to lake shore to spawn under stones. Spawning season is limited to a very short span of time in early spring, late April to early May. During this short spawning season, the male is supposed to have only 2 brood cycles at maximum. At each brood cycle, the male is strictly monogynous, never accepting additional females. Males therefore show a marked mate choice, choosing a larger female regardless of the size of the male himself. Females also choose larger males. However, males are supposed to not waste time in male-male fighting in the natural spawning area. That this very short spawning season and its occurrence in early spring is primarily to avoid interspecific competition with another littorally reproducing goby Yoshinobori,Rhinogobius brunneus, is experimentally demonstrated.     

Spawning,eggs and larvae of the hawkfish,Cirrhitichthys aureus,in an aquarium

Spawning of the hawkfish,Cirrhitichthys aureus, occurred repeatedly between a female and a male in the aquariums of the Marine Science Museum, Tokai University. The pair was collected from Suruga Bay by scuba diving and maintained for 50 days prior to spawning. In early September, 1979, the first successful spawning took place at 17:40 h after several repetitions of a courtship behavior sequence, which was initiated by the male. Spawning continued daily for 104 days between the two fish. Fertilized eggs were spherical, transparent and pelagic, and measured 0.75–0.78 mm in diameter. Hatching took place 19–22.5 hours after fertilization at 26.2–28.4°C. Newly hatched larvae, measuring 2.23–2.28 mm in total length, had a rather slender body with 12+18 = 30 myotomes and a large ellipsoid yolk sac. The front tip of the yolk sac protruded forward beyond the snout of the larvae. A single oil globule was situated in the front part of the yolk sac. The larvae were maintained for 4 days after fertilization. Larval characteristics ofC. aureus bore a close resemblance to those of other cirrhitid species especially in melanophore pigmentation along the dorsal and ventral surfaces.